Euuugh! Eyeball Stew!: Iggy the Urk: Book 3 by Alan MacDonald
Iggy discovers a young member of the Henna tribe lost in the jungle (Henna, so-named for their fiery red hair and penchant for covering their faces in mud). The girl is wearing some rare and precious firestones, which mesmerise the Urks, especially Borg, who devises a new and devious plot to become Chief Urk. Iggy must embark on a dangerous journey to return the Henna girl safely to her tribe in the Cloud Mountains. But when he gets there, the welcome is not exactly what he had in mind. Time for a very cunning plan.